The office of rex sacrorum was created in the earliest days of the Roman republic to execute those sacred functions which had previously been executed by the king. His wife, the regina sacrorum similarly executed those functions which had been executed by the queen.

Nova Roma had no reges and reginae sacrorum until Kal. Ian. ‡P. Ullerio C. Equitio cos. ‡MMDCCLXIVa.u.c., when K. Fabius Buteo Modianus entered this priesthood after his appointment by the collegium pontificum, but the actual consecration and investiture has never took place. K. Buteo Modianus' resigned from his Nova Roman citizenship two months after he occupied this priesthood, leaving Nova Roma without rex sacrorum again.

The rex and regina sacrorum (King and Queen of the Sacred) are a legally married couple that perform various public rites and make announcements of festival days. First among the Priests and members of the collegium pontificum, but subordinate to the pontifex maximus. The rex and regina sacrorum may hold no political posts.